Light absorption and structure of aggregates of dye molecules

Molecular Arrangements in Two-Dimensional J-Aggregate Monolayers of Cyanine Dyes

“…[3] However it was later shown by electron microscopy that the PIC underlying structure is fibrillar at a nanoscale, not a monolayer. [14] One can see from the above consideration, that the introduction of the brickwork arrangement is not necessary both for the explanation of the polarization microscopy data and from a general crystallographic viewpoint.…”

“…via the formation of delocalized Frenkel-type exciton states in stacked adjacent coherently coupled chromophores. [1][2][3] Due to the unique optoelectronic properties, J-and H-aggregates of cyanine dyes have been used long ago as light sensitizers in silver halides color photography [4] and widely studied recently as components for nonlinear optical and photorefractive devices, [5] cavity QED structures, [6] single-mode optical waveguides, [7] lightemitting dopants to electron-hole conducting polymer layers in polymer OLEDs, [8] light-sensitizing agents in complexes with quantum-dots [9] and for biosensing applications. [10] At the nanometer scale, the lateral slippage of transitional dipoles of adjacent π-stacked molecules takes place in J-aggregates and a small slip angle α is formed ( Figure 1a).…”

“…A large molecular slippage (small angle α < 54.7 o ) results in a red shift (in J-aggregates), while a small slippage brings about a blue shift (in H-aggregates). [1][2][3] At a mesoscale, the J-aggregates manifest a complex morphological and structural variability, so that various structures have been observed at different dyes concentrations and solution conditions. For thiacyanine, [11][12][13]17] pseudoisocyanine [14] and some carbocyanine dyes [15][16][17]19] the optical microscopy, [11,12,18] transmission electron microscopy (TEM) [13][14][15][16] and atomic force microscopy (AFM) measurements [11,12,[17][18][19] revealed several morphological groups of J-aggregates such as extended two-dimensional rods, strings and sheets [11,12,15,17,19] and giant tubes, [12,16] fibrils, [14] quasi one-dimensional stripes, twisted ribbons and tubules.…”

“…[17,19] Three basic models of molecular packing arrangements in J-aggregates with the laterally slipped adjacent dye molecules were supposed, i.e. the staircase, ladder and brickwork models [1][2][3] represented schematically in Figure 1. The requirement of small slip angles is valid for all J-aggregates molecular models irrespective of J-aggregate morphology observed at a mesoscale.…”

Crystal structure of 1-ethyl-2-(1-ethyl-H-quinoline-2-ylidenmethylene)- quinolinium nitrate monohydrate, (C23H25N2)NO3 · H2O

“…A one-dimensional brick stone work arrangement is observed in PIC iodide in such a manner that the ring systems are stacked face-to-face [3]. The structure is nearly the same assumed to be present in aqueous solutions of PIC salts and is referred to as a J-aggregate [4][5][6], In contrast, in the described PIC nitrate the cations are joined in an alternating fashion. Every other ring system is stacked face-to-face to its neighbour as mentioned above and for the remaining connections the quinoline rings are shifted, so that they overlap only edge-to-edge.…”